Electric heater.



No. 731,768.1 v PATENTED JUNE 23, 1903i W. A. FULLER..Y

ELECTRIC HEATER. APPLICATION FILED IAB. 26, 19034. N0 MODEL. 2SHEETS-SHEET 1.

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No. 731,768. PATENT-EDVJUNE 23, 1903.

W. A. FULLER. 'I

ELECTRIC HEATER.

APPLICATION FILED MAB. 2e. 190s.

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Patented .Tune 23, 1903.

PATENT OEEIcE.

WILLIAM A. FULLER, OF ROCK ISLAND, ILLINOIS.`

ELECTRIC HEATER.

SPECIFICATION forming part of Letters Patent No. 731,768, dated. June23, 1903.

Application filed March 26, 1903. Serial No. 149,707. (No model.)

To all whom it may concern:

Be it known that I, WILLIAM A. FULLER, a citizen of the United States,residing at Rock Island, in the county of Rock Island, State ofIllinois, have invented certain new and useful Improvements in ElectricHeaters, of which the following is a specification.

The object of my present invention is the production of an electricheater which is compact and durable and which possesses other advantagesof construction, arrangement, and operation over those heretofore known.

My invention consists in certain features of novelty, which will bepointed out in the claims hereto annexed as a part of thisspeciiication.

' For a better understanding of my invention reference may be had to theaccompanying drawings, of which- Figure l is a plan view. Fig. 2 is auelevation, partly broken away; Fig. 3, a perspective view illustratingdetails of construction. Fig. 4 is a diagram illustrating the variouscircuits; and Figs. 5 to 9, inclusive, are diagrams showing various waysin which the heating-conductors may be connected.

The casing or framework of the heater may be formed of cast metal and issubstantially box-like in form. The front of the casing in theconstruction which I have illustrated in the drawings consists of twoplates or'members l I, connected together by screws 2. To these frontpieces are secured two end plates or members 3. The front members I maybe formed with flanges a, to which the end members 3 are connected byscrews 5. A side member 6, curved as shown in Fig. l, closes one side ofthe box-like casing. It is provided with end flanges 7 similar to theflanges 4 of the members l, and is connected to the end members 3 byscrews 8. As shown in Fig. 2, the side piece 6 extends the entiredistance between the ends 3 of the casing. The opposite side of theframe may be closed by a similar piece 6, if desired, or it may be leftin the form shown in the drawings, in which case the heater may beenlarged, if desired, by adding to it other sections or portions similarin general to the one shown. The

,is employed.

Stove-bolts IO, passing through the end pieces 3and the bottoms ofthetrough-shaped supports ll, are provided with nuts on their inner endsand position the supports 11. These supports are arranged in pairs, the0pposite members of each pair being secured to opposite end plates 3.The trough-shaped supports l1 are formed of sheet-brass or the like andopen toward one another, as is clearly shown in Fig. 3. A pair of stripsl2, of sheet-brass or the like, extend between each pair of supports Iland are secured by rivets or the like to the ends and at the rear ofthese supports, as clearly shown in Fig. 3. A similar pair of supportsI3 extend between opposite supports and are secured at the ends ofthesupports on their front sides, as is clearly shown in the drawings.

Each pair of supports l1 and the corresponding strips 12 and 13 form askeleton frame or cage 13', which is supported between the end members 3by the bolts l0. The strips l2 and 13 may be connected intermediate oftheir ends by a support or stay, if desired, as indicated at 132 in Fig.2. If the strips 12 and 13 be made somewhat shorter than the distancebetween the end plates 3, the expansion of the frame 13', due to anincrease in temperature, will not have a tendency to distort the frameor casing, owing to the play which may take place between the ends 3 andthe supports Il, the bolts lO readily permitting this play. Strips ofasbestos or similar material 14, which may be channel-shaped, as shownin Fig. 3, embrace the sides of the skeleton frame 13.

Resistance-wires formed into helices in any suitable manner, as bywinding over a mandrel, are wound one each around each of the boX-likeskeleton frames 13' in the form of helices 14', having rectangularcoils, as is clearly shown in that portion of Fig. 2 in which the plate1 is broken away. In this connection it will of course be understoodthat in the actual heater the coiled resistancewires are seen throughall the interstices of the casing; but in order to avoid confusion inthe drawings I have shown the helix only where the casing is brokenaway. The ends of the resistance-coils are secured to insulators 1G,secured to the framework of the coilsupports, as shown in Fig. 3.Supports of insulating material similar to the insulators 16 may beplaced at intervals along the strips 12 and 13, if desired, in order tomaintain the coils in position. As is well known, however, a helix woundin the manner described has a tendency to increase its grip upon thesupport when it expands upon a temperature increase.

The particular heater which I have illustrated in the drawings isintended to be operated upon a three-phase alternating-current-supplysystem. In the diagram shown in Fig. 4 the three helices 14' are shownas being connected one each through switches 15, 16, and 17 to lines15', 16', and 17', extending from the three-phase supply-lines 18 19 20.The other ends of the coils 14' are connected to switches 21, 22, and23, pivoted at 21', 22', and 23', respectively. The switches 2l, 22, and23 are connected to a bar 24, having a handle 25,by means of which theswitches may be simultanueously operated. lVhen the switches 21, 22,'and23 are in the position shown by full lines in Fig. 4, the coils 14 areconnected at one side by means of a shortcircuit connection 26. When theswitches 2l, 22, and 23 are in the 'position shown in dotted lines inFig. 4, the coils are connected to the lines 16', 17', and 15',respectively.

The various arrangements of the circuits in the heater and correspondingvariations in the amount of energy consumed and heat produced bymanipulations of the switches 15, 16, 1.7, 21, 22, and 23 areillustrated in Figs. 5 to 9, inclusive. In Fig. 5 the switches 21, 22,and 23 are in the dotted-line position and the switches 15, 16, and 17are all closed. In this case the three heating-coils are all in use,being arranged in delta. In the arrangement shown in Fig. 6 the switches21, 22, and 23 are also in the dotted-line position and the switches 1Gand 17 are closed. The switch 15, however, is open. In this arrangementtwo of the heating-coils are in operation and the energy consumed istwo-thirds of that when the circuits are arranged as shown in Fig. 5. Inthe arrangement shown in Fig. 7 the switches 15, 16, and 17 are closed,and the switches 21= 22, and 23 are in the full-line position. In thisarrangement all of the coils are in operation, but are connected in thestar relation. In the diagram illustrated in Fig. 8 the switches 2l, 22,and 23 are in the dotted line position and the switch 17 is closed. Theswitches 15 and 16 are open, however, so that only one coil is inoperation. In the arrangement shown in Fig. 9 the switches 2l, 22, and23 are in the full-line position and the switches 16 and 17 are closed,the switch 15 being open. This results in placing two of theheating-coils in series between two ofthe supply-lines. It is seen,therefore, that the arrangement of switches described gives a very widevariation in the heating effect upon simple manipulations of theswitches. In practice it will of course be understood that the switch 21may be the standard form of three-blade double-throw pivoted switch orany other of the ordinary forms of switches instead of that shown. Therectangular form of the coil-supports and the coil wound thereon makes avery compact arrangement. The construction of the coil-support out ofsheet metal is especially advantageous, owing to its cheapness and tothe mechanical strength which can be obtained with a minimum amount ofmaterial.

The skeleton construction of the coil-supports permits a very efficientair circulation through the heaters.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. In combination, a plurality of bars arranged to form an open box-likestructure, and a helical conductor wound in a helix around said bars.

2. In an electric heater, a resistance-conductor formed into a helix,the helical conductor in turn being formed into a helix the coils ofwhich are substantially rect-angular.

3. In combination, a casing, groups of metallic bars extending fromopposite lsides of said casing, the bars in each group being arranged toform an open substantially rectangular casing, a helical conductor woundin a helix about said bars, and means for insulating said conductor fromsaid bars.

4. In combination, a plurality of metal bars secured together to form arectangular cage, and a helical resistance conductor wound about saidbars.

5. In combination, a plurality of strips of sheet metal arranged to forma cage having a substantially rectangularsection,and a helicalresistance-conductor wound in a helix about said cage, the coils of saidhelix being substantially rectangular.

6. In combination, a pair of supports, a skeleton frame formed of sheetmetal held between said supports by means allowing the frame to expand,and a resistance-conductor wound on said frame.

7. In an electric heater, a coi-l-support substantially rectangular incross-section, insulation embracing opposite sides of said support, anda conductor wound about said support.

S. In an electric heater, a metallic support- IOC) IIO

ing-casing having a box-like form, a pluraltion or in the star relationto said supply syslo ity of coil-supports lying side by side in saidtem. casing, the coil-supports being substantially In Witness whereof Ihave hereunto set my rectangular in cross-section, and conductors handthis 21st day of March, 1903. Wound about said coil-supports.

9. In combination With an electric heater WILLIAM A FULLER having threeresistance-conductors, a three- I Witnesses:

phase current-supply system, and means for B. E. STINSON, connecting theconductors in the delta rela- J. J. OBRIEN.

